Justin Gunnar Walter Chancellor, born on November 19, 1971, in England, is a bassist known for his work with Tool and Peach. He began his musical journey as a bass player for Slice of Life during his time at Tonbridge School. In the early 1990s, he joined Peach, an alternative rock band from Canada. With Peach, Chancellor released Giving Birth to a Stone in 1994 and supported Tool on their European tour that year before the band disbanded in 1995. Following Peach's breakup, Chancellor moved to the United States and joined Tool full-time, replacing Paul D'Amour during the recording of Ænima, released in 1996. With Tool, he contributed to notable albums such as Lateralus (2001), 10,000 Days (2006), and Fear Inoculum (2019). Chancellor has also collaborated with various artists, including Isis, Intronaut, The Fusion Syndicate, Primus, Death Grips, Author & Punisher, Night Verses, and Adam Jones.